Blowpipe



Feb. 14? 1939.

s. R. OLDHAM LowPPE F'iled June l8,\ 1935 ATTORNEY Patented Feb. 14, 1939 UNITED ASTATES Btowrnl:`

Samuel R. Oldham, Elizabeth, N. J., assignor, by mesne assignments, to Union Carbide and Carbon Corporation, a corporation of New York Application June 18, 1935, Serial No. 27,155

12 Claims.

This invention relates to blowpipes and more particularly heavy duty blowpipes employing fuelgas at low pressure.v 'I'he invention is particularly useful in connection with welding blowpipes,

5 to which use however, the invention is not limited.

In operations wherein large quantities of fuelgas are required under low pressure it is frequently desirable to provide blowpipe apparatus I of adequate capacity in compact light and convenient form. It is also important to reduce backring, and to prevent flashbacks or sustained burning of gas within the blowpipe.

Prior known blowpipes of the type which eml ploy low-pressure fuel-gas are limited to a comparatively small fuel-gas consumption range, seldom exceeding 80 cubic feet per hour. Variation of the fuel-gas consumption below this limit has heretofore been accomplished by employing t0 injectors having diierent size exit orices, and by varying the clearance between the injector head and the bore of the blowpipe. While the rate of fuel-gas consumed increases with the increase in clearance between the injector head and 55 the blowpipe bore, the ashback resistance decreases proportionally therewith. VThus, a limit will be reached beyond which flashbacks and sustained burning in the torch will occur.

One object of the invention therefore is to provide a blowpipe of convenient size which will supply at all times a sufcient volume of low pressure fuel-gas and still possess maximum flashback resistance. Another object is the provision of such a blowpipe in a form which will insure a l5 steady and constant ow of fuel-gas. A further object is the provision of such a blowpipe in a form which will have improved flashback resistance as well as improved means for hunting the eilect of ashbacks: that is to say, a form which L0 will insure smothering of backflres and prevent ilashbacks or continued burning inside the blowpipe. Other objects will appear upon consideration of the present speciiication and the accompanying drawing.

The invention is shown by way of illustration in its application to a welding blowpipe in the accompanying drawing, in which;

Fig. 1 is a longitudinal mid-section through a blowpipe constructed in accordance with the in- ;o vention;

Pis. 2 is a cross-section on the line II-II of Fig. i;

PIL. 3 is a cross-section on the line HI-III of Fig. l; i5 Pig. 4 is a longitudinal mld-section of an In- (Cl. S- 27.0

jector similar to that illustrated in Fig. 1 showing a modified form; and

Fig. 5 is a cross-section on the line V-V of Fig. 4, the scale being twice the scale employed in Fig. 4. 5

In order to realize the objects of the invention,

a blowpipe is provided which is so formed or streamlined as to impose a minimum obstruction to the gas ow, and provide unrestricted back ilow when temporary interruption of the ame l0 occurs. Thus, large fuel-gas passages, a straightway fuel-gas valve, and a long, tapered injector nozzle are ordinarily employed. Furthermore, an interchangeable injector nozzle may be provided with longitudinal slots extending inwardly from l5 its periphery, to increase fuel-gas capacityof the blowpipe without increasing the clearance between the injector nozzle and thebore of the blowpipe. A fuel-gas chamber of substantial size is formed in the handle; the combustion-supporting gas tube extends preferably centrally through this chamber; and a plurality of fuelgas passages, preferably equally spaced about the combustion-supporting gas tube inthe front body of thehandle, permit substantially unrestricted 26 passage and even distribution of fuel gas to the nozzle.

Referring now more particularly to the drawin'g, it will be seen that it shows a blowpipe com-w prising a tubular handle H having a valve block s0 B secured to its rear end through whichlblock the separate gases pass before reachingthe handle, and at the other end, a stem S through which the combustible mixture passes to a tip (not shown) where combustion takes place.

Fuelgas is delivered to the valve block B through a nipple IIl, whence it enters a, passage II in the valve block which leads to a valve chamber I2, in which a valve I3 acts'under control of a uted head I 4. A bore I5 connects the 40 is constructed of substantial size and is adapted to maintain a considerable volume of combustible gas within the handle.' It will further be apparent that a minimum obstrucdon to the pasu sage of fuel-gas from the nipple I0 to the chamber I6 is provided in the valve block, the valve I3 being of the straightway type, and it being possible to draw a straight line from the entrance to the valve block through the valve chamber I2 to the fuel-gas chamber I6.

Combustion-supporting gas `(usually oxygen) enters the blowpipe through a nipple 20, whence it passes to a valve 2I in the valve block B. From the valve 2| the combustion-supportinggas passes through a bore 22 in the valve block. A combustion-supporting gas tube 23 has one end thereof disposed in the bore 22 and fastened therein. The combustion-supporting gas tube 23 extends substantially'axially through the fuel-gas chamber I6, and has its forward end fastened in an axial bore 24 in the connecting nipple I9.

'I'he forward end of the handle H is engaged by an annular bushing 25 which extends forwardly thereof and which is internally threaded as at 26 to accommodate external threads 21 on the connecting nipple I9. Thus, the forward end of the handle, the forward end of the cylindrical shell I1, and the forward end of the combustion-supporting gas tube 23 are all connected by the connecting nipple I9 and the annular bushing 2 5.

'I'he stem S is connected with the handle H by means of a hollow nut 28, having internal threads 29 thereon which coact with external threads 30 on the connecting nipple I9. The hollow nut 28 has an internal annular shoulder 3l which bears against an external annular shoulder 32 on the stem S adjacent the end thereof. A split ring 33 fits into an annular depression 34 extending circumferentially of the stem S immediately beyond the forward end of the hollow nut 28 when the latter is in position and prevents the latter from moving with respect to the stem when in place.

The rear end of the stem S is internally enlarged and has, adjacent the rear end of the enlargement, internal threads 35 adapted' to engage -external threads 36 upon an injecting and mixing nozzle-31. The'forward end of the injecting and mixing nozzle 31 (hereafter referred to as the injector) extends into the enlargement in the rear end of the stem, and forms therewith an annular passage as well as a mixer for mixing the fuel-gas and the combustion-supporting gas which enter the blowpipe. 'I'he injector 31 has a central passageway 38 extending axially therethrough. Surrounding this 'central passageway, spaced equally therefrom and extending for part of the length thereof, a plurality of shorter passageways 39 are formed in the injector.. The passages 39 convey the fuel-gas to,

` and distribute it evenly about the annular passage between the forward end of the injecting nozzle 3l and the rear end of the stem S.

A tubular extension 461 carries the axial passageway 38 an appreciable distance back of the surrounding passageways 39; and when the hollow nut '28 is screwed upon the connecting nipple i8 as far as it will go the beveled exterior end lll of the tubular extension 46 seats into the front end of the axial bore 24 in the connecting nipple i9. Thus, a tight t is effected between the axial passageway 38 and the axial bore 24 in the connecting nipple i9.. Similarly, that part of the injector 3l which lies beyond the surrounding passageways 39 is exteriorly beveled to form a seat 42, and is pressed into a corresponding interiorly beveled seat in the forward end of the connecting nipple I9. thereby forming a tight joint therewith. Because of the shape of the forward end of the connecting nipple I9, an annular chamber 43 is formed between the injector and the nipple with which the surrounding passageways 39 communicate.

A plurality of passageways 44 surround the axial bore 24 in the connecting nipple I9, the several passageways being preferably equally spaced from the axial bore. Communication is thus provided between the fuel-gas chamber I6 and the chamber 43 between the injector and the nipple I9.

The forward end of the injector forms'a head 45 disposed within and spaced from the chamber in the enlarged rear end of the stem S; and the forward end of the central passageway 38 in the injector opens into this space. A constricted mixing throat 46 extends forwardly in the stem from the forward end of the head 45 to the bore 41 of the stem.

From the foregoing it will be seen that combustion-supporting gas controlled by the valve 2| will passr readily through the combustion-supporting gas tube 23 in the handle, thence into the axial bore in the connecting nipple I9, and thence through the central passageway 38 in the injector 31 from which it will be discharged in a stream from the injector into the mixing throat 46 to pass into the bore 41 of the stem S. At the same time, the fuel-gas, controlled by the valve I3, will enter the chamber I6, will pass through the surrounding passageways 44 into the annular chamber 43 and thence through the passageways 39 in the injector to the annular space surrounding the head 45 of the injector; after which it will pass through the gradually tapered conical way to the forward end of the head 45, join the combustion-supporting gas, and be projected into the mixing throat 46.

The passageways 44 in the connecting nipple I9 and the surrounding passageways 39 in the injector 31 are constructed and arranged to offer a minimum of obstruction to the flow of the fuelgas. Their size and number are such that freeA passage of the fuel-gas in adequate volume may reach the mixing throat 46. The cJmbustionsupporting gas being under higher pressure will tend to create a suction in the aspirating space surrounding the head and will lthereby draw fuelgas from the passageways 39 into the mixing throat 46.

From the foregoing, it will be evident that the surrounding passageways in the connecting nipple I9 and the injector 31 afford an equally free passage when back-pressure occurs in` the mixing throat 46 which is in excess of the fuel-gas pressure. rll'hus, backiires may pass easily into the fuel-gas chamber I6. Since the combustion-supporting gas is at a higher pressure than the fuelgas, ashbacks will not enter the injector passage 38, but will follow the path of least resistance and enter into the chamber i6. However, the volume of fuel-gas contained in this chamber is large, as has been indicated, and therefore, tends to smother the backfire in the chamber I6.

Blowpipes constructed in accordance with the i terrupted, is restored, the resulting mixture of oxygen from the injector and burned gases drawn into the mixing throat 46, will extinguish any flame which might remain adjacent the mixing throat, thereby tending to prevent sustained burning, or flashback in the blowpipe.

In order to increase the fuel-gas consumption range, without affecting the injector action or the flashback resistance, an injector 31 like that illustrated in Fig. 4 may be interchangeably employed. In such an injector longitudinal slots 48 are formed in the head 45' extending inwardly from the periphery thereof. Thus, additional cross section is provided to permit free passage of fuel-gas to the mixing throat, without increasing the clearance between the head 45 and the bore of stem S. The number of slots 48 may vary and the dimensions of the exit orifices of passage 38 may also vary depending upon the increased fuel-gas consumption necessary for the given work. The surrounding passageways 39 are exactly the same in this construction as in that illustrated in Fig. 1 and are equally spaced from the central passageway 38, being disposed one behind each of the longitudinal slots 48 in the head 45 (see Fig. 5). From the foregoing, it is apparent that a low-pressure blowpipe of an exceptionally wide fuel-gas consumption range may be provided by interchangeably employing injector nozzles 31 or 31 having the desired number and arrangement of passages 39 and provided with or without slots 48, in combination with an improved means for adequately limiting the effect of flashbacks.

The embodiments herein described and shown in the accompanying drawing are presented merely as examples of how the invention may be applied. Other forms differing in detail, but not in principle, from those here disclosed will, of course, suggest themselves to those skilled in th art.

I claim:

1. For use in a blowpipe, a connecting nipple having an axial passage and a plurality of eccentric passages therein, said nipple having a surface thereon contiguous to the axial passage therein for contact with a gas tube adapted for connection therewith, a coaxial surface thereon beyond the eccentric passages for contact with a second gas tube, said nipple also having thereon two coaxial threaded portions, one for accommodation of an annular bushing to which the blowpipe handle is joined, and one for accommodation of a hollow nut by which the blowpipe stem is attached.

2. For use in a blowpipe, a connecting nipple having an axial passage and a plurality of parallel eccentric passages therethrough, said nipple also having thereon an annular interiorly beveled face beyond the forward ends of the eccentric passages and an annular interiorly beveled face at the forward end of the axial passage, in combination with a nozzle having an axial passage and a plurality of parallel eccentric passages therethrough, said nozzle also having thereon an annular exterioriy beveled face beyond the rearward ends of the eccentric passages and an exteriorly beveled face beyond the rearward end of the axial passage, and means for holding said nipple and said nozzle in associated position with the beveled faces adjacent the axial passages, and the beveled faces beyond the eccentric passages respectively in engagement.

3. An oxy-acetylene blowpipe comprising oxygen and acetylene inlets; a voluminous acetylene trai passageway for discharging a stream of com- .gen is projected to aspirate acetlylene through conducting chamber associated with the acetylene inlet; an oxygen conduit associated with the. oxygen inlet; an injecting nozzle; a stem adapted to accommodate a gas mixing chamber and tol support said injecting nozzle; means associated with, and adapted to connect said acetylene conducting chamber and oxygen conduit to said injecting nozzle comprising an element including means adapted to form gas-tight-forming seats with complementary means on said injecting nozzle; and means mounted on said stem and adapted to maintain said gas-tight-forming seat means in cooperative relation with said 'complementary means.

4. An Oxy-acetylene blowpipe as claimed in claim 3, in which said element is provided with unrestricted acetylene gas passages.

5-. An Oxy-acetylene blowpipe as claimed 'in claim 3, in which said injecting nozzle is 4provided with unrestricted acetylene gas passages.

6. An Oxy-acetylene blowpipe as claimed in claim 3, in which said injecting nozzle is provided with a head forming an annular acetylene gas passage with a portion of said blowpipe, and said head is provided with auxiliary gas passage means adapted to accommodate a relatively large volume of acetylene gas.

7. A low pressure blowpipe comprising the combination with an injector nozzle having a cenbustion-supporting gas; and means providing a fuel-gas aspirating sp'ace coaxial with said passageway and into which said stream of combustion-supporting gas is discharged; of streamlined fuel-gas passage means comprising a fuel-gas inlet, a backfire smotheringchamber adapted to contain an ample volume of fuel gas to smother any backfire liable to occur within said blowpipe, and unrestricted parallel passages between said chamber and said aspirating space; whereby in the event of a backfire,- gas backow is unobsaid backfire smothering chamber, the products of combustion then being aspirated by the uninterrupted stream of combustion-supporting gas to extinguish any remaining flashback in the blowpipe.

8. A low pressure blowpipe comprising: an oxygen injector nozzle having an orificefor projecting a high velocity stream of oxygen; means providing an acetylene inlet, a valve, a cylindrical shell and a conical way Vcoaxially disposed relative 'to said orifice; and a stem having an aspirating chamber into which said stream of oxysaid conical way; said cylindrical shell comprising an acetylene chamber adapted to contain a sufficient volume of acetylene to smother a backfire; said acetylene inlet,-valve, shell and conical way being streamlined to provide for the smooth and unobstructed forward flow of the acetylene to render the same highly responsive to the velocity of the oxygen stream projected by said nozzle such streamlining of the acetylene flow at the same time functioning to 'provide for the unrestricted backward flow of the acetylene in the event of a backfire so that in such event the back pressure is absorbed by the backward iiow of acetylene, and the resulting products of combustion thereafter at once flow forward as in the normal operationl of the blowpipe to extinguish wholly any lingering ashback in the blowpipe.

9. A low pressure blowpipe comprising the combination with an injector nozzle having a central structed and the whole backfire freely enters e passageway for projecting a stream of combustion-supporting gas; means providing a fuel-gas aspirating space coaxial with said centralpassageway; and means providing a gasijniixing throat into which is projected the strea'rfn" Teombustion-supporting gas and fuel-gas;` of"fuel gas passage means comprising in series afuelgas inlet, a valve block having a fuel-gas passage, valve chamber and bore, a bell shaped tube, a cylindrical shell, a connecting nipple having parallel passageways, an annular chamber, parallel passageways in said nozzle, a cylindrical way, and a gradually tapered conical way merging into said aspirating space; said fuel-gas passage means being adapted to provide for the unobstructed substantially straight streamlined forward flow of `a large supply offuel gas to said aspirating space in accordance with the velocity of said stream of combustion-supporting gas; said cylindrical shell providing a fuel-gas chamber of suflicient size to contain ian adequate volume of fuel gas for smothering a backfire; said fuelgas passage means at the same time providing for the unrestricted backflow of gas in the event of a backfire, in which event the backfire is smothered by the large volume of fuel gas within said fuel-gas chamber, and any lingering flashback is extinguished by the subsequent aspiration of the resulting products of combustion by said stream of combustion-supporting gas.

10. A low pressure blowpipe comprising the combination with an injector nozzle vhaving a central passageway for projecting a stream of combustion-supporting gas; means providing a fuel-gas aspirating space coaxial with said central passageway; and means providing a gas mixing throat into which the stream of combustionsupporting gas and fuel gas is projected; of fuelgas passage means comprising in series a fuelgas inlet, a valve block having a valve chamber, a cylindrical shell, a connecting nipple having parallel passages, an annular chamber, parallel passages in said nozzle, a cylindrical way, and a gradually tapered conical way merging into said aspirating space; said cylindrical shell constituting a backfire smothering chamber of ample fuel gas capacity for that purpose; said inlet and said valve chamber being alined in parallel relation with the major axis of said cylindrical shell to provide a substantially straight-through fuelgas flow path delivering to said back nre smothering chamber; said parallel passages in said nipple, said annular chamber, said parallel passages in said nozzle, said cylindrical way and said conical way providing an unrestricted streamlined fuel-gas ow path between said backre smothering chamber and said aspirating space; whereby in the event of a backfire, unrestricted backflow of the fuel gas causes the backfire to enter freely and be smothered by the large volume of fuel gas within said backre smothering chamber, and the resulting products of combustion are aspirated by the combustion-supporting gas to extinguish any flashback left burning adjacent said gas mixing throat.

11. A low pressure blowpipe comprising:A a valve block having an oxygen bore and an acetylene passage; a tubular handle connected to said valve block; a tubular shell disposed within said tubular handle in spaced relation thereto; a bellshaped tube connecting said shell and handle adjacent said block; an 'oxygen tube disposed centrally of said shell in spaced relation thereto to provide a cylindrical chamber of large size and substantial volume for the acetylene; said chambergrbeing in line with said acetylene passager,cpnnecting'nipple having a central oxygen passage and parallel acetylene passages; said acetylene passages being arranged in line with said cylindric' f cha'mber, an annular bushing connecting saidl nipple and handle; an injector and mixing nozzle having a central oxygen passage and parallel acetylene passages; the nozzle acetylene passages and the nipple acetylene passages being in communication through an annular chamber; a stem connected to said nozzle; and a nut connecting said nipple and nozzle; said stem and the head of said nozzle being spaced to provide a cylindrical acetylene passage which merges into a conical passage; there being a throat in said Stem into which the oxygen from the orifice of said injector is projected to aspirate the acetylene to provide a fuel mixture; said acetylene passages being adapted to encourage backfiring within said cylindrical chamber for the purpose of smothering the same therein, so that the subsequent forward movement of the resulting products of combustion wholly extinguishes any lingering flashback in the blowpipe.

12. A blowpipe for use with a fuel gas and a combustion-supporting gas, comprising the combination with a nozzle having a central gas passageway for discharging one of said gases, and means providing a mixing space for said fuel gas and combustion-supporting gas, said space being coaxial with said central gas passageway and into which said one gas is discharged; of a streamlined gas passage means for said other gas comprising a gas inlet, a voluminous backfire-receiving chamber adapted to contain an ample volume of such other gas to receive any f backfire liable to occur within said. blowpipe; and unrestricted passage means surrounding said nozzle between said chamber and said mixing space; whereby in the event of a backfire, back flow of said other gas is unobstructed and the 

